Apparatus and process for gasification of carbonaceous materials to produce syngas

ABSTRACT

A process and apparatus are provided for gasification of a carbonaceous material. The process produces a raw syngas that can be further processed in a tar destruction zone to provide a hot syngas. The process includes contacting said carbonaceous material with molecular oxygen-containing gas in a gasification zone to gasify a portion of said carbonaceous material and to produce a first gaseous product. A remaining portion of the carbonaceous material is contacted with molecular oxygen-containing gas in a burn-up zone to gasify additional portion of the carbonaceous material and to produce a second gaseous product and a solid ash. The first gaseous product and said second gaseous product are combined to produce a raw syngas that includes carbon monoxide (CO), carbon dioxide (CO 2 ) and tar. The raw syngas is contacted with molecular oxygen containing gas in a tar destruction zone to produce said hot syngas.

This application claims the benefit of U.S. Provisional Application Nos.61/516,646, 61/516,704 and 61/516,667 all filed Apr. 6, 2011, all ofwhich are incorporated in their entirety herein by reference.

An apparatus and process is provided for gasification of carbonaceousmaterials to produce producer gas or synthesis gas or syngas thatincludes carbon monoxide and hydrogen.

BACKGROUND

Gasification of carbonaceous materials to produce producer gas orsynthesis gas or syngas comprising carbon monoxide and hydrogen is wellknown in the art. Typically, such a gasification process involves apartial oxidation or starved-air oxidation of carbonaceous material inwhich a sub-stoichiometric amount of oxygen is supplied to thegasification process to promote production of carbon monoxide asdescribed in WO 2009/154788. As described in WO 2009/154788, agasification process can further be influenced by addition of one ormore of steam and carbon dioxide (CO₂). Success of a gasificationprocess greatly depends on quality of syngas produced. Increased contentof carbon monoxide (CO) and hydrogen (H₂) is desirable in syngasproduced. In other words, contents of diluents such as carbon dioxide(CO₂), nitrogen (N₂) should be as low as possible especially for use ofproduct syngas for heating value or for producing chemicals.

Various mineral matters often form part of carbonaceous materials. Whilethe hydro-carbonaceous part of carbonaceous materials converts to CO,CO₂ and H₂, the mineral matters get separated from thehydro-carbonaceous part and together with any unconverted carbonaceousmaterial or unconverted carbon form ash. The amount and composition ofash (e.g. carbon content) can have an impact on the smooth running ofthe gasifier as well as on the disposal of ash. Melting andagglomeration of ash in the gasifier may cause slagging and clinkerformation that can lead to partial or complete blocking of gasifier. Itis, therefore, advantageous to have a gasification process that avoidsthe melting of ash. It is also advantageous to have a low content ofunburned fuel or carbon in ash.

James T. Cobb, Jr. (“Production of Synthesis Gas by BiomassGasification,” James T. Cobb, Jr., Proceedings of the 2007 SpringNational AIChE Meeting, Houston, Tex., Apr. 22-26, 2007) describes aConsutech Gasifier (BRI Energy LLC), the first stage of which is astandard step-grate combustor (frequently used as an MSW incinerator)that operates as a gasifier at 950° F. using oxygen-enriched air. Thesecond stage is a heat treater that operates at 2000-2250° F. and usesminimal oxygen to crack tars.

WO 2009/154788 describes a two stage gasifier in which carbonaceousmaterial is fed to the first stage in which air, oxygen-enriched air orpure oxygen can be injected at a controlled rate. The first stagetemperature and oxygen input is controlled such that only partialoxidation of carbonaceous material occurs. The gaseous product from thefirst stage moves to the second stage. Ash is removed from the firststage. Pure oxygen is introduced into the second stage in order toaccomplish cracking and partial oxidation of any tar contained in thegaseous stream from the first stage.

A two stage gasifier such as that described in WO 2009/154788 can beeffective in producing syngas from various waste carbonaceous materialsand good quality syngas can be produced, however, a high carbon contentis generally observed in ash produced from this gasification process.

SUMMARY

A process and apparatus are provided for gasification of a carbonaceousmaterial. The process produces a raw syngas that can be furtherprocessed in a tar destruction zone to provide a hot syngas. The hotsyngas has a molar ratio of CO/CO₂ in the hot syngas is greater thanabout 0.75 and a ratio of carbon content of solid ash to carbon contentof carbonaceous material feed is less than about 0.1. The carbon contentof the solid ash is less than about 10%.

A process is provided for gasification of a carbonaceous material toproduce a raw syngas. The process includes contacting said carbonaceousmaterial with a first molecular oxygen-containing gas and optionallywith one or more of steam and CO₂ in a gasification zone to gasify aportion of said carbonaceous material and to produce a first gaseousproduct. A remaining portion of the carbonaceous material is contactedwith a second molecular oxygen-containing gas and optionally with one ormore of steam and CO₂ in a burn-up zone to gasify an additional portionof said carbonaceous material and to produce a second gaseous productand a solid ash comprising carbon. The first gaseous product and secondgaseous product are combined to produce the raw syngas. The raw syngashas a CO/CO₂ molar ratio greater than about 0.75 and ratio of carboncontent of solid ash to carbon content of carbonaceous material feedless than about 0.1. The carbon content of the solid ash is less thanabout 10%.

In another aspect, the mass of total oxygen per unit mass of totalcarbon in carbonaceous material feed entering gasification zone is lessthan mass of total oxygen per unit mass of total carbon in anunconverted portion of carbonaceous material feed entering burn-up zone.The gasification zone may include one or more gasification hearths andthe burn-up zone may include one or more burn-up hearths. One or more ofsaid gasification hearths accomplish preheating of the carbonaceousmaterial by heat exchange with one or more of said first gaseous productand second gaseous product.

In another aspect, a ratio of total amount of molecular oxygen containedin the first molecular oxygen containing gas and the second molecularoxygen containing gas to the total amount of molecular oxygen requiredto completely oxidize all carbon contained in carbonaceous material feedto carbon dioxide is in a range of 0.1 to 0.9. In accordance with theprocess, molecular oxygen is introduced into the gasification zone andburn-up zone at a rate of about 0 to about 75 lb-mole per tone ofcarbonaceous material on a dry basis. The temperature of thegasification zone and burn-up zone is not greater than 800° C.

In another aspect, a process for gasification of a carbonaceous materialto produce a hot syngas. The process includes contacting saidcarbonaceous material with a first molecular oxygen-containing gas andoptionally with one or more of steam and CO₂ in a gasification zone togasify a portion of said carbonaceous material and to produce a firstgaseous product. A remaining portion of the carbonaceous material iscontacted with a second molecular oxygen-containing gas and optionallywith one or more of steam and CO₂ in a burn-up zone to gasify additionalportion of the carbonaceous material and to produce a second gaseousproduct and a solid ash comprising carbon. The first gaseous product andsaid second gaseous product are combined to produce a raw syngas thatincludes carbon monoxide (CO), carbon dioxide (CO₂) and tar. The rawsyngas has a CO/CO₂ molar ratio greater than about 0.75. The raw syngasis contacted with a third molecular oxygen containing gas in a tardestruction zone to produce said hot syngas. The tar destruction zonehas temperature greater than about 900° C. The molar ratio of CO/CO₂ inthe hot syngas is greater than about 0.75 and a ratio of carbon contentof solid ash to carbon content of carbonaceous material feed is lessthan about 0.1. The carbon content of the solid ash is less than about10 weight %.

A gasification apparatus is provided that includes a gasification zonethat includes one or more hearths; a burn-up zone continuous with thegasification zone, the burn-up zone including one or more hearths,wherein the gasification and burn-up zones are effective for providing araw syngas having a CO/CO₂ molar ratio greater than about 0.75 and ratioof carbon content of solid ash to carbon content of carbonaceousmaterial feed is less than about 0.1; and a tar destruction zoneeffective for receiving the raw syngas from the gasification and burn-upzones through a connecting zone. In one aspect, the gasification zoneincludes up to 10 hearths. In one aspect, the burn-up zone includes upto 5 hearths. In another aspect, the gasification apparatus includes atleast one solids transfer device effective for moving carbonaceousmaterial from the gasification zone to the burn-up zone. Thegasification apparatus may also include at least one gas inlet in thegasification zone, burn-up zone and tar destruction zone.

BRIEF DESCRIPTION OF FIGURES

The above and other aspects, features and advantages of several aspectsof the process will be more apparent from the following drawings.

FIG. 1 is a schematic diagram of a gasification-apparatus that includesa gasification zone and a burn-up zone. Referring now to FIG. 1, thegasification-apparatus (10) includes a gasification zone (103) and aburn-up zone (200). The gasification zone includes one inlet for addinggas (e.g., oxygen containing gas, steam, carbon dioxide): inlet 102; theburn-up zone includes one inlet for adding gas: inlet 202. Acarbonaceous material feed (101) can be added into the gasification zone(103). A stream of solid ash (205) can be removed from burn-up zone(200). A stream of raw syngas (105) can be removed from the gasificationzone (103).

FIG. 2 is a schematic diagram of an aspect of a gasification-apparatusthat includes a gasification zone and a burn-up zone wherein thegasification zone includes four sections or hearths. Referring now toFIG. 2, the gasification-apparatus (11) includes a gasification zone(113) and a burn-up zone (230). The gasification zone (113) includesfour gasification hearths: Hearth-I (310), Hearth-II (320), Hearth-III(330), and Hearth-IV (340). Each gasification hearth includes one inletfor adding gas: gas inlet 111 to Hearth-I, gas inlet 121 to Hearth-II,gas inlet 131 to Hearth-III, and gas inlet 141 to Hearth-IV. The burn-upzone includes one inlet for adding gas: gas inlet 202. A carbonaceousmaterial feed (101) can be added into Hearth-I (entry hearth) of thegasification zone (113). A stream of solid ash (205) can be removed fromthe burn-up zone (230). A stream of raw syngas (105) can be removed fromthe gasification zone (113).

FIG. 3 is a schematic diagram of an aspect of a gasification-apparatusthat includes a gasification zone and a burn-up zone wherein thegasification zone includes four sections or hearths and the burn-up zoneincludes two sections or hearths. Referring now to FIG. 3, thegasification-apparatus (12) includes a gasification zone (123) and aburn-up zone (232). The gasification zone (123) includes fourgasification hearths: Hearth-I (410), Hearth-II (420), Hearth-III (430),and Hearth-IV (440). Each gasification hearth includes one inlet foradding gas: gas inlet 411 to Hearth-I, gas inlet 421 to Hearth-II, gasinlet 431 to Hearth-III, and gas inlet 441 to Hearth-IV. The burn-upzone includes two burn-up hearths: Hearth-V (416), Hearth-VI (220). Eachburn-up hearth includes one inlet for adding gas: gas inlet 511 toHearth-V, and gas inlet 521 to Hearth-VI. A carbonaceous material feed(101) can be added into Hearth-I (entry hearth) of the gasification zone(123). A stream of solid ash (205) can be removed from Hearth-VI (exithearth) of the burn-up zone (232). A stream of raw syngas (105) can beremoved from the gasification zone (123).

FIG. 4 is a schematic diagram of an aspect of a gasification-apparatusthat includes a gasification zone, a burn-up zone and a tar reductionzone wherein the gasification zone includes five sections or hearths.Referring now to FIG. 4, the gasification-apparatus (13) includes agasification zone (143), a burn-up zone (500), a connecting zone orthroat (300) and a tar reduction zone (400). The gasification zone (143)includes five gasification hearths: Hearth-I (110), Hearth-II (120),Hearth-III (130), Hearth-IV (140), and Hearth-V (150). Each gasificationhearth includes one inlet for adding gas: gas inlet 611 to Hearth-I, gasinlet 621 to Hearth-II, gas inlet 631 to Hearth-III, gas inlet 641 toHearth-IV and gas inlet 651 to Hearth-V. The burn-up zone includes oneinlet for adding gas: gas inlet 202. The connecting zone or throat (300)includes one inlet for adding gas: gas inlet 301. A carbonaceousmaterial feed (101) can be added into Hearth-I (entry hearth) of thegasification zone (143). A stream of solid ash (205) can be removed fromthe burn-up zone (500). A stream of hot syngas (405) can be removed fromthe tar reduction zone (400).

Corresponding reference characters indicate corresponding componentsthroughout the several views of the drawings. Skilled artisans willappreciate that elements in the figures are illustrated for simplicityand clarity and have not necessarily been drawn to scale. For example,the dimensions of some of the elements in the figures may be exaggeratedrelative to other elements to help to improve understanding of variousaspects of the present process and apparatus. Also, common butwell-understood elements that are useful or necessary in commerciallyfeasible aspects are often not depicted in order to facilitate a lessobstructed view of these various aspects.

DETAILED DESCRIPTION Definitions

Unless otherwise defined, the following terms as used throughout thisspecification for the present disclosure are defined as follows and caninclude either the singular or plural forms of definitions belowdefined:

The term “about” modifying any amount refers to the variation in thatamount encountered in real world conditions, e.g., in the lab, pilotplant, or production facility. For example, an amount of an ingredientor measurement employed in a mixture or quantity when modified by“about” includes the variation and degree of care typically employed inmeasuring in an experimental condition in production plant or lab. Forexample, the amount of a component of a product when modified by “about”includes the variation between batches in a multiple experiments in theplant or lab and the variation inherent in the analytical method.Whether or not modified by “about,” the amounts include equivalents tothose amounts. Any quantity stated herein and modified by “about” canalso be employed in the present disclosure as the amount not modified by“about”.

“Carbonaceous material” as used herein refers to carbon rich materialsuch as coal, and petrochemicals. However, in this specification,carbonaceous material includes any carbon material whether in solid,liquid, gas, or plasma state. Among the numerous items that can beconsidered carbonaceous material, the present disclosure contemplates:carbonaceous material, carbonaceous liquid product, carbonaceousindustrial liquid recycle, carbonaceous municipal solid waste (MSW ormsw), carbonaceous urban waste, carbonaceous agricultural material,carbonaceous forestry material, carbonaceous wood waste, carbonaceousconstruction material, carbonaceous vegetative material, carbonaceousindustrial waste, carbonaceous fermentation waste, carbonaceouspetrochemical coproducts, carbonaceous alcohol production coproducts,carbonaceous coal, tires, plastics, waste plastic, coke oven tar,fibersoft, lignin, black liquor, polymers, waste polymers, polyethyleneterephthalate (PETA), polystyrene (PS), sewage sludge, animal waste,crop residues, energy crops, forest processing residues, wood processingresidues, livestock wastes, poultry wastes, food processing residues,fermentative process wastes, ethanol coproducts, spent grain, spentmicroorganisms, or their combinations.

The term “fibersoft” or “Fibersoft” or “fibrosoft” or “fibrousoft” meansa type of carbonaceous material that is produced as a result ofsoftening and concentration of various substances; in an examplecarbonaceous material is produced via steam autoclaving of varioussubstances. In another example, the fibersoft can include steamautoclaving of municipal, industrial, commercial, medical wasteresulting in a fibrous mushy material.

The term “municipal solid waste” or “MSW” or “msw” means wastecomprising household, commercial, industrial and/or residual waste.

The term “syngas” or “synthesis gas” means synthesis gas which is thename given to a gas mixture that contains varying amounts of carbonmonoxide and hydrogen. Examples of production methods include steamreforming of natural gas or hydrocarbons to produce hydrogen, thegasification of coal and in some types of waste-to-energy gasificationfacilities. The name comes from their use as intermediates in creatingsynthetic natural gas (SNG) and for producing ammonia or methanol.Syngas includes use as an intermediate in producing synthetic petroleumfor use as a fuel or lubricant via Fischer-Tropsch synthesis andpreviously the Mobil methanol to gasoline process. Syngas consistsprimarily of hydrogen, carbon monoxide, and some carbon dioxide, and hasless than half the energy density (i.e., BTU content) of natural gas.Syngas is combustible and often used as a fuel source or as anintermediate for the production of other chemicals.

“Ton” or “ton” refers to U.S. short ton, i.e. about 907.2 kg (2000 lbs).

As used herein, the term “tar” includes, without limitation, a gaseoustar, a liquid tar, a solid tar, a tar-forming substances, or mixturesthereof, which generally comprise hydrocarbons and derivatives thereof.A large number of well known tar measurement methods exist that may beutilized to measure tar. One large family of techniques includesanalytical methods based on liquid or gas phase chromatography coupledwith a detector. The most frequent detectors in the case of measurementof tars are the flame-ionization detector (FID) and the massspectrometer. Another family of techniques includes spectrometricmethods, which include detecting and analyzing a spectrum. This is forexample infrared, ultraviolet (UV) or luminescence spectrometry, andLIBS (Laser-Induced Breakdown Spectroscopy) technique. Another techniquefor monitoring of combustion gases is FTIR (Fourier Transform InfraRed)infrared spectrometry. Miscellaneous documents mention this technique,such as for example WO2006015660, WO03060480 and U.S. Pat. No.5,984,998.

There exist other known electronic methods which allow continuousmonitoring of tars. These techniques include detectors withelectrochemical cells and sensors with semiconductors. Variousgravimetric techniques may also be utilized for tar measurements. In oneaspect, the amount of tar may be expressed as equivalent ppm of carbon.In this aspect, the hydrocarbon may be benzene or an alcohol, such asmethanol. In this aspect, reducing content of tar may mean a tarconcentration equivalent or tar equivalents corresponding to less thanabout 10 ppm benzene.

DETAILED DESCRIPTION

The following description is not to be taken in a limiting sense, but ismade merely for the purpose of describing the general principles ofexemplary embodiments. The scope of the invention should be determinedwith reference to the claims.

A processes and apparatus is provided for gasification of carbonaceousmaterial to produce syngas. In the process, a gasification-apparatus isused for gasification of a carbonaceous material. Thegasification-apparatus includes a gasification zone and a burn-up zone.A carbonaceous material feed is introduced in the gasification zone ofthe gasification-apparatus. A first molecular oxygen containing gas issupplied to the gasification zone and thus the carbonaceous materialfeed is treated with molecular oxygen in order to initiate andfacilitate chemical transformation of carbonaceous material. A portionof the carbonaceous material feed is gasified in the gasification zoneto produce a first gaseous product. Supply of oxygen into thegasification-apparatus and especially into the gasification zone iscontrolled in order to preferentially promote formation of carbonmonoxide from carbonaceous material. A sub-stoichiometric amount ofoxygen is supplied in order to promote production of carbon monoxide.This action causes incomplete conversion of carbonaceous material in thegasification zone; only a portion of carbonaceous material is gasifiedin the gasification zone. The remaining portion of carbonaceous materialis transferred to the burn-up zone. A second molecular oxygen containinggas is supplied to the burn-up zone and thus the remaining portion ofcarbonaceous material is treated with molecular oxygen in order tofacilitate chemical transformation of unconverted portion ofcarbonaceous material into gaseous components. An additional portion ofsaid carbonaceous material is thus gasified in the burn-up zone toproduce a second gaseous product. The first gaseous product and thesecond gaseous product are combined to form a raw syngas.

In one aspect the gasification zone and burn-up zone are physicallyseparate units. In one aspect the gasification zone and burn-up zone areparts of one single unit. The gasification zone may be any gasificationequipment disclosed in prior art such as and not limited to moving bed,fixed bed, fluidized bed, entrained flow, counter-current (“up draft”),co-current (“down draft”), counter-current fixed bed, co-current fixedbed, counter-current moving bed, co-current moving bed cross draft,hybrid, cross flow, cross flow moving bed, or a part thereof. Theburn-up zone may be any gasification equipment disclosed in prior artsuch as and not limited to moving bed, fixed bed, fluidized bed,entrained flow, counter-current (“up draft”), co-current (“down draft”),counter-current fixed bed, co-current fixed bed, counter-current movingbed, co-current moving bed cross draft, hybrid, cross flow, cross flowmoving bed, or a part thereof. In one aspect flow of solid is downwardand flow of gas is upward in at least a part of the burn-up zone. In oneaspect, the gasification zone is a cross flow unit and the burn-up zoneis a counter current unit. In one aspect, the gasification zone is across flow unit and the burn-up zone is a counter current moving bedunit. In one aspect, the gasification zone is a cross flow moving bedunit and the burn-up zone is a counter current unit with gas flowingupward and solid moving downward.

In one aspect, the gasification zone may include one or more sections orgasification hearths for contacting said carbonaceous material with afirst molecular oxygen-containing gas and optionally with one or more ofsteam and CO₂ to gasify a portion of said carbonaceous material and toproduce a first gaseous product. In various aspects, the gasificationzone includes 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 sections or gasificationhearths. In one aspect, the burn-up zone includes one or more burn-uphearths for contacting remaining portion of said carbonaceous materialwith a second molecular oxygen-containing gas to gasify an additionalportion of said carbonaceous material and to produce a second gaseousproduct and solid ash. In various aspects, the burn-up zone may include1, 2, 3, 4, or 5 sections or burn-up hearths. In one aspect, thegasification-apparatus includes one gasification hearth and one burn-uphearth. In one aspect, the gasification-apparatus includes twogasification hearths and one burn-up hearth. In one aspect, thegasification-apparatus includes three gasification hearths and oneburn-up hearth. In one aspect, the gasification-apparatus includes fourgasification hearths and one burn-up hearth. In one aspect, thegasification-apparatus includes five gasification hearths and oneburn-up hearth. In one aspect, the gasification-apparatus includes twogasification hearths and two burn-up hearths. In one aspect, thegasification-apparatus includes three gasification hearths and twoburn-up hearth. In one aspect, the gasification-apparatus includes fourgasification hearths and two burn-up hearth. In one aspect, thegasification-apparatus includes five gasification hearths and twoburn-up hearth. In one aspect, one or more of said gasification hearthsmay be used to accomplish preheating of said carbonaceous material. Saidpreheating can be accomplished by heat exchange with one or more of saidfirst gaseous product and said second gaseous product. In one aspect,one or more of said burn-up hearths provide arrangement for up-flow ofgas and down-flow of solid.

Raw syngas produced in the process described above often includes tarthat is undesirable for downstream operation and use. Reduction of tarcontent of raw syngas can be accomplished by contacting said raw syngaswith a third molecular oxygen containing gas in a tar destruction zone.Partial oxidation and/or cracking of tar contained in said raw syngas isaccomplished in the tar reduction zone. A hot syngas is thus producedwith no or a substantially low tar content. Therefore, in one aspect,said gasification-apparatus includes a tar reduction zone for treatingsaid raw syngas comprising said first gaseous product and said secondgaseous product with a third molecular oxygen containing gas. The tarreduction zone can be a horizontal or a vertical chamber with circularor square or rectangular or any other cross section. The tar reductionzone can be inclined to the horizontal or vertical direction. The tarreduction zone can be connected to the gasification zone or to theburn-up zone or to both the gasification zone and the burn-up zonethrough one or more connecting zones or throats. In one aspect, the tarreduction zone is connected to the gasification zone through oneconnecting zone. A gas inlet can be attached directly to the tarreduction zone. One or more gas inlets can be attached to one or moreconnecting zones (throats). The third molecular oxygen containing gascan be introduced directly into the tar reduction zone. The thirdmolecular oxygen containing gas can be introduced into the tar reductionzone through one or more gas inlets attached to one or more connectingzones.

Gas inlets for introduction of the first molecular oxygen containing gascan be attached to the gasification zone or one or more hearthscontained therein. Gas inlets for introduction of the second molecularoxygen containing gas can be attached to the burn-up zone or one or morehearths contained therein. Steam or CO₂ may also be introduced throughone or more of these gas inlets. In one aspect, one or more of firstmolecular oxygen containing gas, steam and CO₂ may be introduced throughthe gas inlets attached to the gasification zone or to one or morehearths contained therein. In one aspect, one or more of first molecularoxygen containing gas, steam and CO₂ are pre-mixed prior to supplying tothe gas inlets attached to the gasification zone or to one or morehearths contained therein. In one aspect, one or more of secondmolecular oxygen containing gas, steam and CO₂ are pre-mixed prior tosupplying to the gas inlets attached to the burn-up zone or to one ormore hearths contained therein.

In one aspect the gasification zone includes an entry hearth and one ormore additional gasification hearths, wherein the carbonaceous materialfeed is introduced into the entry hearth. In one aspect, the firstmolecular oxygen containing gas is not supplied through gas inletattached to the entry hearth. In one aspect, no gas inlet is attachedthe entry hearth. The carbonaceous material introduced in the entryhearth optionally comes in contact with one or more of the first and thesecond gaseous product that contain heat. Heat contained in said one ormore of the first and the second gaseous product may thus be exchangedwith the carbonaceous material thereby accomplishing drying orpre-drying of carbonaceous material. A dried or pre-dried carbonaceousmaterial is thus transferred to subsequent hearths. Thermaldecomposition or gasification of a portion of carbonaceous material mayalso occur in the entry hearth.

One or more mechanical devices such as transfer rams may be used tofacilitate movement of solid inside the gasification zone e.g. from onegasification hearth to the next and inside the burn-up zone, e.g. fromone burn-up hearth to the next and to facilitate transfer of solid fromthe gasification zone to the burn up zone. In one aspect, the bottom ofthe gasification zone is positioned at a level above the bottom of theburn-up zone in order to facilitate movement of solid. In one aspect,the bottom of any gasification hearth is placed at a level lower thanthe bottom of the previous hearth as solid moves from the entry hearthto the burn-up zone. In one aspect, the bottom of any burn-up hearth isplaced at a level lower than the bottom of the previous hearth as solidmoves towards the exit hearth. In an aspect wherein the gasificationzone includes an entry hearth and one or more additional gasificationhearths, no transfer ram is used in the entry hearth; in this entryhearth, solid is pushed into the next gasification hearth by feedingmore feed solid (carbonaceous material). In one aspect, one or moretransfer rams (ash removal rams) are used in the burn-up zone to removesolid ash. Several methods can be employed to remove solid ash out ofthe burn-up zone. In one aspect, a water seal is used in which an ashremoval ram pushes solid ash into a pool of water, using water as a sealin order to minimize, preferably avoid, air leakage into the burn-upzone. The wet ash is then moved out of the water using a conveyor belt.In another aspect, the ash is removed through a lock-hopper system tominimize, preferably avoid air leakage into the burn-up zone. Forexample double ash doors comprising an upper ash door and a lower ashdoor can be used to provide the seal. In one aspect, keeping the lowerash door closed to provide a seal, the upper ash door is opened to allowash to fall downward into a non-combustion zone in which the ash cancool down. In order to remove ash, the upper ash door is closed first toprovide the seal and then the lower ash door is opened and an ashremoval ram pushes cooled ash out of gasifier. This method removes dryash and can have advantage if ash has any direct usage as no drying isrequired prior to such direct usage of ash.

A high enough temperature is attained in the gasification-apparatus tofacilitate gasification of carbonaceous material. However, thetemperature is maintained low enough so that non-carbonaceous mineralmatter contained in carbonaceous material feed may not melt inside thegasification-apparatus. In other words, temperature in any part of thegasification zone or of the burn-up zone may not exceed the meltingpoint temperature of ash comprising said non-carbonaceous mineralmatter. Typically, a gas phase temperature not exceeding 800° C. ismaintained in the gasification zone as well as in the burn-up zone. Inone aspect, temperatures in the gasification zone and in the burn-upzone are maintained in the range 260-800° C. Thus solid ash comprisingsaid non-carbonaceous mineral matter accumulates in the burn-up zone anda stream of solid ash is removed from the burn-up zone.

The tar reduction zone provides a short contact time but is operated ata high enough temperature in order to ensure adequate destruction oftar. The temperature in the tar reduction zone can be between 900 and2000° C. Reaction time or contact time in the tar reduction zone can bein a range of about 0.5 to about 5 seconds.

Raw syngas is produced that may include carbon monoxide (CO) and carbondioxide (CO₂). It is desirable to have more CO and less CO₂ in the rawsyngas. In one aspect, the CO/CO₂ molar ratio in said raw syngas isgreater than about 0.75. In one aspect, the CO/CO₂ molar ratio in saidraw syngas is greater than about 1.0. In one aspect, CO/CO₂ molar ratioin said raw syngas is greater than about 1.5. Hot syngas may includecarbon monoxide (CO) and carbon dioxide (CO₂). It is desirable to havemore CO and less CO₂ in the hot syngas. In one aspect, the CO/CO₂ molarratio in said hot syngas is greater than about 0.75. In one aspect, theCO/CO₂ molar ratio in said hot syngas is greater than about 1.0. In oneaspect, CO/CO₂ molar ratio in said hot syngas is greater than about 1.5.

In addition to containing non-carbonaceous mineral matter, solid ash mayinclude unconverted carbon or unconverted carbonaceous matter. In oneaspect, carbon content of said solid ash is less than about 10 wt %. Inone aspect, carbon content of solid ash is less than 5 wt %. In oneaspect, ratio of carbon content of solid ash to carbon content ofcarbonaceous material feed is less than about 0.1. In one aspect, ratioof carbon content of solid ash to carbon content of carbonaceousmaterial feed is less than about 0.01.

The carbon content of ash and carbon content of carbonaceous materialfeed refers to carbon or a chemical that contains carbon. In thisaspect, numerous known techniques may be utilized to measure carboncontent. Some examples of techniques that may be used to measure carboninclude and are not limited to loss-on-ignition (LOI) tests,themogravimetric analysis (TGA), laser probe based optical methods,methods using microwave radiation, methods using nuclear magneticresonance (NMR), and various ASTM methods (see for example ASTM D6316).

Undesirable hot spots might be created in said gasification-apparatus inone or more of the gasification zone and the burn-up zone, or hearthscontained therein, due to uneven distribution of molecular oxygencontaining gas in said carbonaceous material feed. This may cause poorquality in raw syngas produced. Hot spots can also cause localizedmelting of ash. Formation of hot spots can be reduced or prevented byinjecting one or more of steam and carbon dioxide into one or more ofsaid gasification zone and said burn-up zone. Thus, in order to preventundesirable hot spots, carbonaceous material feed may be treated withsteam along with molecular oxygen in the gasification zone. Carbonaceousmaterial feed may be treated with CO₂ gas along with molecular oxygen inthe gasification zone. Carbonaceous material feed may be treated withsteam along with molecular oxygen in the burn-up zone. Carbonaceousmaterial feed may be treated with CO₂ gas along with molecular oxygen inthe burn-up zone. Thus the first molecular oxygen-containing gas mayinclude one or more of steam and carbon dioxide gas and the secondmolecular oxygen-containing gas may include one or more of steam andcarbon dioxide gas.

As described above, a sub-stoichiometric amount of oxygen is supplied tothe gasification apparatus in order to promote production of carbonmonoxide. Therefore, in one aspect, the ratio of the total amount ofmolecular oxygen contained in the first molecular oxygen containing gasand the second molecular oxygen containing gas to the total amount ofmolecular oxygen required to completely oxidize all carbon contained incarbonaceous material feed to carbon dioxide is in a range of 0.1 to0.9. In one aspect, the ratio of the total amount of molecular oxygencontained in the first molecular oxygen containing gas and the secondmolecular oxygen containing gas to the total amount of molecular oxygenrequired to completely oxidize all carbon contained in carbonaceousmaterial feed to carbon dioxide is in a range of 0.1 to 0.9. In oneaspect, ratio of total amount of molecular oxygen contained in the firstmolecular oxygen containing gas, the second molecular oxygen containinggas and the third molecular oxygen containing gas to the total amount ofmolecular oxygen required to completely oxidize all carbon contained incarbonaceous material feed to carbon dioxide is in a range of 0.1 to0.9. In one aspect, ratio of total amount of molecular oxygen containedin the first molecular oxygen containing gas, the second molecularoxygen containing gas and the third molecular oxygen containing gas tothe total amount of molecular oxygen required to completely oxidize allcarbon contained in carbonaceous material feed to carbon dioxide is in arange of 0.1 to 0.9.

Careful control of temperatures in the gasification zone and in theburn-up zone and rates of supplies of oxygen into the gasification zoneand into the burn-up zone are required in order to achieve low contentof carbon in solid ash and high CO/CO₂ ratio in raw syngas. A higheramount to oxygen per unit amount of available carbon in carbonaceousmaterial is provided in the burn-up zone compared to the amount tooxygen per unit amount of available carbon in carbonaceous materialprovided in the gasification zone. Thus the mass of total oxygen perunit mass of total carbon in carbonaceous material feed enteringgasification zone is less than mass of total oxygen per unit mass oftotal carbon in unconverted portion of carbonaceous material feedentering burn-up zone. Mass of total oxygen per unit mass of totalcarbon in carbonaceous material feed entering gasification zone can bein a range comprising 0.1 to 2.0 lb/lb. Mass of total oxygen per unitmass of total carbon in unconverted portion of carbonaceous materialfeed entering burn-up zone can be in a range comprising 0.25 to 2.5lb/lb. Any chemically bonded oxygen contained in the carbonaceousmaterial as well as chemically bonded oxygen contained in any steam orCO₂ that is supplied may participate in the chemical transformation andgasification of carbonaceous material. It is, therefore, important toconsider any chemically bonded oxygen contained in the carbonaceousmaterial as well as chemically bonded oxygen contained in any steam orCO₂ that is supplied in determining amount of molecular oxygen to besupplied.

In order to supply molecular oxygen said first molecular oxygencontaining gas may include air. In order to supply molecular oxygen saidfirst molecular oxygen containing gas may include enriched air. In orderto supply molecular oxygen said first molecular oxygen containing gasmay include pure oxygen. In order to supply molecular oxygen said secondmolecular oxygen containing gas may include air. In order to supplymolecular oxygen said second molecular oxygen containing gas may includeenriched air. In order to supply molecular oxygen said second molecularoxygen containing gas may include pure oxygen.

In one aspect, molecular oxygen containing gas is distributedhorizontally inside one or more gasification hearths. In one aspect,molecular oxygen containing gas is distributed vertically in one or moreburn-up hearths. In one aspect, introduction of molecular oxygencontaining gas in one or more burn-up hearths is discontinuous. In oneaspect, one or more of gas inlets are equipped with cooling device. Inone aspect, one or more of said cooling devices are water jackets on thegas inlets. In one aspect, one or more gas inlets extend out of transferrams. In one aspect, additional nozzles on the surface of transfer ramsare used for introduction of molecular oxygen containing gas.

The third molecular oxygen containing gas may include air. The thirdmolecular oxygen containing gas may include enriched air. The thirdmolecular oxygen containing gas may include pure oxygen.

In one aspect, the same molecular oxygen containing gas is supplied toone or more of gasification zone, burn-up zone and tar reduction zone.In one aspect, different molecular oxygen containing gases are suppliedto the gasification zone, the burn-up zone and the tar reduction zone.

Total amount of molecular oxygen introduced in the gasification zone andthe burn-up zone through said molecular oxygen containing gas can be ina range of about 0 to about 75 lb-moles per ton of carbonaceous materialon a dry basis. In various aspects, amounts of molecular oxygen suppliedto the gasification zone and to the burn-up zone may include a rangeselected from: 0 to 5, 0 to 50, 0 to 75, 5 to 10, 10 to 15, 15 to 20, 20to 25, 25 to 30, 30 to 35, 35 to 40, 40 to 45, 45 to 50, 50 to 55, 55 to60, 60 to 65, and 65 to 70 lb-moles per ton of carbonaceous materialfeed on a dry basis. In various aspects, amounts of molecular oxygensupplied to one or more of the gasification hearths and burn-up hearthsmay include a range selected from: 0 to 5, 0 to 50, 0 to 75, 5 to 10, 10to 15, 15 to 20, 20 to 25, 25 to 30, 30 to 35, 35 to 40, 40 to 45, 45 to50, 50 to 55, 55 to 60, 60 to 65, and 65 to 70 lb-moles per ton ofcarbonaceous material feed on a dry basis.

Total amount of steam introduced in the gasification zone and theburn-up zone can be in a range of about 0 to about 50 lb-moles per tonof carbonaceous material feed on a dry basis. In various aspects, amountof steam added in one or more of the gasification zone and the burn-upzone may include a range selected from: 0 to 5, 5 to 10, 10 to 15, 15 to20, 20 to 25, 25 to 30, 30 to 35, 35 to 40, 40 to 45, and 45 to 50lb-moles per ton of carbonaceous material feed on a dry basis. Invarious aspects, amount of steam added in one or more of thegasification hearths and the burn-up hearths may include a rangeselected from: 0 to 5, 5 to 10, 10 to 15, 15 to 20, 20 to 25, 25 to 30,30 to 35, 35 to 40, 40 to 45, and 45 to 50 lb-moles per ton ofcarbonaceous material feed on a dry basis.

Total amount of carbon dioxide gas introduced in the gasification zoneand the burn-up zone can be in the range of about 0 to about 50 lb-molesper ton of carbonaceous material feed on a dry basis. In variousaspects, amount of carbon dioxide gas added in one or more of thegasification zone and the burn-up zone may include a range selectedfrom: 0 to 5, 5 to 10, 10 to 15, 15 to 20, 20 to 25, 25 to 30, 30 to 35,35 to 40, 40 to 45, and 45 to 50 lb-moles per ton of carbonaceousmaterial feed on a dry basis. In various aspects, amount of carbondioxide gas added in one or more of the gasification hearths and theburn-up hearths may include a range selected from: 0 to 5, 5 to 10, 10to 15, 15 to 20, 20 to 25, 25 to 30, 30 to 35, 35 to 40, 40 to 45, and45 to 50 lb-moles per ton of carbonaceous material feed on a dry basis.

In one aspect, both steam and carbon dioxide gas are introduced in oneor more of the gasification and burn-up zones. In one aspect, one ormore of steam and carbon dioxide gas are injected in one or more linessupplying oxygen to blend in with oxygen lines just before distributionnozzle.

The total amount of oxygen added in the tar reduction zone can be in arange of about 0 to about 75 lb-moles per ton of carbonaceous materialfeed on a dry basis. In various aspects, amounts of molecular oxygensupplied to the tar reduction zone may include a range selected from: 0to 5, 0 to 50, 0 to 75, 5 to 10, 10 to 15, 15 to 20, 20 to 25, 25 to 30,30 to 35, 35 to 40, 40 to 45, 45 to 50, 50 to 55, 55 to 60, 60 to 65,and 65 to 70 lb-moles per ton of carbonaceous material feed on a drybasis.

In one aspect of said gasification-apparatus, pressure is maintained ata negative (sub-atmospheric) pressure in order to avoid leakage offlammable and toxic syngas into the surroundings. However, this actionleads to leakage of air into the gasifier, e.g. around moving rams anddoors. Such leakage of air may cause loss of raw syngas. It may alsocause a dilution of raw syngas. Thus a careful control of the gasifierdraft is necessary to reduce air leakage. Gasifier draft can becontrolled at a negative (sub-atmospheric) pressure in a range of 0.01to 0.50 inch water. One way of accomplishing this is by manually settinga fan speed (to control hot syngas temperature) and adjusting solids andoxygen feed rates to control draft. Draft control can also be achievedwith flow control of one or more of carbon dioxide and steam under thecarbonaceous material bed. In one aspect, for example during start-up,pressure may be atmospheric or greater than atmospheric.

Air admitted with the carbonaceous material feed can be reduced by usinga screw feeder which compresses the carbonaceous material feed. Airadmitted with the carbonaceous material feed can also be reduced byusing purged lock hoppers. In one aspect, for example during start-up,air leakage may be allowed.

In one aspect, a methane containing gas such as natural gas isintroduced in one or more of the gasification zone, the burn-up zone andthe tar reduction zone especially in order to facilitate start-up.

The carbonaceous material fed to the gasifier may include selectionfrom: carbonaceous material, carbonaceous liquid product, carbonaceousindustrial liquid recycle, carbonaceous municipal solid waste (MSW ormsw), carbonaceous urban waste, carbonaceous agricultural material,carbonaceous forestry material, carbonaceous wood waste, carbonaceousconstruction material, carbonaceous vegetative material, carbonaceousindustrial waste, carbonaceous fermentation waste, carbonaceouspetrochemical co-products, carbonaceous alcohol production co-products,carbonaceous coal, tires, plastics, waste plastic, coke oven tar,fibersoft, lignin, black liquor, polymers, waste polymers, polyethyleneterephthalate (PETA), polystyrene (PS), sewage sludge, animal waste,crop residues, energy crops, forest processing residues, wood processingresidues, livestock wastes, poultry wastes, food processing residues,fermentative process wastes, ethanol co-products, spent gain, spentmicroorganisms, or their combinations.

In one aspect of the present disclosure the carbonaceous material fed tothe gasifier includes a plurality of carbonaceous materials selectedfrom carbonaceous material, carbonaceous liquid product, carbonaceousindustrial liquid recycle, carbonaceous municipal solid waste (MSW ormsw), carbonaceous urban waste, carbonaceous agricultural material,carbonaceous forestry material, carbonaceous wood waste, carbonaceousconstruction material, carbonaceous vegetative material, carbonaceousindustrial waste, carbonaceous fermentation waste, carbonaceouspetrochemical co-products, carbonaceous alcohol production co-products,carbonaceous coal, tires, plastics, waste plastic, coke oven tar,fibersoft, lignin, black liquor, polymers, waste polymers, polyethyleneterephthalate (PETA), polystyrene (PS), sewage sludge, animal waste,crop residues, energy crops, forest processing residues, wood processingresidues, livestock wastes, poultry wastes, food processing residues,fermentative process wastes, ethanol co-products, spent grain, spentmicroorganisms, or their combinations.

In one aspect, said carbonaceous material includes water. In one aspect,said carbonaceous material includes less than about 50 wt % water. Inone aspect, said carbonaceous material includes less than about 25 wt %water. In one aspect said carbonaceous material includes less than about15 wt % water. In one aspect, moisture content of said carbonaceousmaterial is decreased by pre-drying.

In one aspect, said carbonaceous material includes greater than about 25wt % carbon on a dry or water free basis. In one aspect saidcarbonaceous material includes greater than about 50 wt % carbon on adry or water free basis. In one aspect, said carbonaceous materialincludes oxygen in the range of about 0 to about 50 wt % oxygen on a dryor water free basis. In one aspect said carbonaceous material includeshydrogen in the range of about 0 to about 25 wt % hydrogen on a dry orwater free basis. In one aspect, said carbonaceous material includesless than about 25 wt % ash on a dry or water free basis. In one aspectsaid carbonaceous material includes less than about 15 wt % ash on a dryor water free basis.

In various aspects, the temperature in one or more of the gasificationzone and burn-up zone can be selected from temperature ranges: 260-270°C., 270-280° C., 280-290° C., 290-300° C., 300-310° C., 310-320° C.,320-330° C., 330-340° C., 340-350° C., 350-360° C., 360-370° C.,370-380° C., 380-390° C., 390-400° C., 400-410° C., 410-420° C.,420-430° C., 430-440° C., 440-450° C., 450-460° C., 460-470° C.,470-480° C., 480-490° C., 490-500° C., 500-510° C., 520-530° C.,530-540° C., 540-550° C., 550-560° C., 560-570° C., 570-580° C.,580-590° C., 590-600° C., 600-610° C., 610-620° C., 620-630° C.,630-640° C., 640-650° C., 650-660° C., 660-670° C., 670-680° C.,680-690° C., 690-700° C., 700-710° C., 710-720° C., 720-730° C.,730-740° C., 740-750° C., 750-760° C., 760-770° C., 770-780° C.,780-790° C., and 790-800° C.

In various aspects, the temperature in one or more of the gasificationhearths and the burn-up hearths can be selected from temperature ranges:260-270° C., 270-280° C., 280-290° C., 290-300° C., 300-310° C.,310-320° C., 320-330° C., 330-340° C., 340-350° C., 350-360° C.,360-370° C., 370-380° C., 380-390° C., 390-400° C., 400-410° C.,410-420° C., 420-430° C., 430-440° C., 440-450° C., 450-460° C.,460-470° C., 470-480° C., 480-490° C., 490-500° C., 500-510° C.,520-530° C., 530-540° C., 540-550° C., 550-560° C., 560-570° C.,570-580° C., 580-590° C., 590-600° C., 600-610° C., 610-620° C.,620-630° C., 630-640° C., 640-650° C., 650-660° C., 660-670° C.,670-680° C., 680-690° C., 690-700° C., 700-710° C., 710-720° C.,720-730° C., 730-740° C., 740-750° C., 750-760° C., 760-770° C.,770-780° C., 780-790° C., and 790-800° C.

In one aspect, temperatures in the gasification zone and the burn-upzone are same. In one aspect, temperatures in the gasification zone andthe burn-up zone are different. In one aspect, the temperature in theburn-up zone is greater than the temperature in the gasification zone.In one aspect, the temperatures in all hearths in the gasification zoneand the burn-up zone are same. In one aspect, different hearths aremaintained at different temperatures. In one aspect, the temperature inone or more burn-up hearth(s) can be greater than the temperature in oneor more gasification hearth(s). In one aspect the temperature increasesfrom the entry hearth of the gasification zone to the exit hearth of theburn-up zone.

In various aspects, the temperature in the tar reduction zone can beselected from temperature ranges: 900-910° C., 910-920° C., 920-930° C.,930-940° C., 940-950° C., 950-960° C., 960-970° C., 970-980° C.,980-990° C., 990-1000° C., 1000-1010° C., 1010-1020° C., 1020-1030° C.,1030-1040° C., 1040-1050° C., 1050-1060° C., 1060-1070° C., 1070-1080°C., 1080-1090° C., 1090-1100° C., 1100-1110° C., 1110-1120° C.,1120-1130° C., 1130-1140° C., 1140-1150° C., 1150-1160° C., 1160-1170°C., 1170-1180° C., 1180-1190° C., 1190-1200° C., 1200-1210° C.,1210-1220° C., 1220-1230° C., 1230-1240° C., 1240-1250° C., 1250-1260°C., 1260-1270° C., 1270-1280° C., 1280-1290° C., 1290-1300° C.,1300-1310° C., 1310-1320° C., 1320-1330° C., 1330-1340° C., 1340-1350°C., 1350-1360° C., 1360-1370° C., 1370-1380° C., 1380-1390° C.,1390-1400° C., 1400-1410° C., 1410-1420° C., 1420-1430° C., 1430-1440°C., 1440-1450° C., 1450-1460° C., 1460-1470° C., 1470-1480° C.,1480-1490° C., 1490-1500° C., 1500-1510° C., 1510-1520° C., 1520-1530°C., 1530-1540° C., 1540-1550° C., 1550-1560° C., 1560-1570° C.,1570-1580° C., 1580-1590° C., 1590-1600° C., 1600-1610° C., 1610-1620°C., 1620-1630° C., 1630-1640° C., 1640-1650° C., 1650-1660° C.,1660-1670° C., 1670-1680° C., 1680-1690° C., 1690-1700° C., 1700-1710°C., 1710-1720° C., 1720-1730° C., 1730-1740° C., 1740-1750° C.,1750-1760° C., 1760-1770° C., 1770-1780° C., 1780-1790° C., 1790-1800°C., 1800-1810° C., 1810-1820° C., 1820-1830° C., 1830-1840° C.,1840-1850° C., 1850-1860° C., 1860-1870° C., 1870-1880° C., 1880-1890°C., 1890-1900° C., 1900-1910° C., 1910-1920° C., 1920-1930° C.,1930-1940° C., 1940-1950° C., 1950-1960° C., 1960-1970° C., 1970-1980°C., 1980-1990° C., 1990-2000° C.

Specific aspects of the present disclosure are described with referenceto FIGS. 1 to 4. Thus FIG. 1 provides a schematic diagram of an aspectof the present disclosure wherein the gasification-apparatus (10)includes a gasification zone (103) comprising one gasification hearthand a burn-up zone (200) comprising one burn-up hearth. Carbonaceousmaterial feed (101) is introduced in gasification zone. A firstmolecular oxygen containing gas (102) is supplied to the gasificationzone. A first gaseous product is produced in the gasification zone.Unconverted portion of carbonaceous material is transferred from thegasification zone to the burn-up zone. A second molecular oxygencontaining gas (202) is supplied to the burn-up zone. A second gaseousproduct is produced in the burn-up zone. Solid ash (205) is removed fromthe burn-up zone. The first and the second gaseous products are combinedto produce a raw syngas stream (105) that is removed from gasificationzone.

FIG. 2 presents a schematic diagram of gasification-apparatus (10)wherein gasification zone includes four gasification hearths: Hearth-I,i.e. entry hearth (310), Hearth-II (320), Hearth-III (330), andHearth-IV (340). Carbonaceous material feed (101) is introduced in thegasification zone in Hearth-I (entry hearth). Inside the gasificationzone, solid from Hearth-I, i.e. entry hearth, is transferred toHearth-II; solid from Hearth-II is transferred to Hearth-Ill; and solidfrom Hearth-III is transferred to Hearth-IV. Solid comprisingunconverted portion of carbonaceous material is transferred fromHearth-IV of gasification zone into the burn-up zone (230). A firstmolecular oxygen containing gas is supplied to different gasificationhearths through gas inlets 111, 121, 131, and 141 that are attached toHearth-I, Hearth-II, Hearth-III, and Hearth-IV respectively. In oneaspect, no molecular oxygen containing gas is introduced into Hearth-I(entry hearth). A second molecular oxygen containing gas is supplied tothe burn-up zone through gas inlet 202. Solid ash (205) is removed fromthe burn-up zone.

One or more mechanical devices (not shown in diagram) such as transferrams may be used to facilitate movement of solid from one hearth to thenext or from one zone to the next, e.g. in FIG. 2, from Hearth-I toHearth-II, from Hearth-II to Hearth-III, from Hearth-III to Hearth-IV,from Hearth-IV of the gasification zone to the burn-up zone. In oneaspect, no transfer ram is used in Hearth-I, the entry hearth, whereinsolid is pushed into next hearth by feeding more feed solid(carbonaceous material).

FIG. 3 presents a schematic diagram of an aspect ofgasification-apparatus (10) wherein the gasification zone (123) includesfour hearths: Hearth-I, i.e. entry hearth (410), Hearth-II (420),Hearth-III (430), and Hearth-IV (440). The burn-up zone (232) includestwo hearths: Hearth-V (416), and exit hearth, Hearth-VI (220).Carbonaceous material feed (101) is introduced in the gasification zonein Hearth-I (entry hearth). Inside the gasification zone, solid fromHearth-I, i.e. entry hearth, is transferred to Hearth-II; solid fromHearth-II is transferred to Hearth-III; and solid from Hearth-III istransferred to Hearth-IV. Solid comprising unconverted portion ofcarbonaceous material is transferred from Hearth-IV of gasification zoneinto Hearth-V of the burn-up zone. Inside the burn-up zone, solid fromHearth-V is transferred to Hearth-VI (exit hearth). A first molecularoxygen containing gas is supplied to different gasification hearthsthrough gas inlets 411, 421, 431, and 441 that are attached to Hearth-I,Hearth-II, Hearth-III, and Hearth-IV respectively. In one aspect, nomolecular oxygen containing gas is introduced into Hearth-I (entryhearth). A second molecular oxygen containing gas is supplied todifferent gasification hearths through gas inlets 511, and 521 that areattached to Hearth-V, and Hearth-VI (exit hearth) respectively. Solidash (205) is removed from Hearth VI (exit hearth) of the burn-up zone.

One or more mechanical devices (not shown in diagram) such as transferrams may be used to facilitate movement of solid from one hearth to thenext or from one zone to the next, e.g. in FIG. 3, from Hearth-I toHearth-II, from Hearth-II to Hearth-III, from Hearth-III to Hearth-IV,from Hearth-IV of the gasification zone to Hearth-V of the burn-up zone,and from Hearth-V to Hearth-VI. In one aspect, no transfer ram is usedin Hearth-I, the entry hearth, wherein solid is pushed into next hearthby feeding more feed solid (carbonaceous material).

FIG. 4 presents a schematic diagram of one aspect ofgasification-apparatus (13) comprising a gasification zone (143),burn-up zone (500), and a tar reduction zone (400) wherein thegasification zone (143) includes five hearths: Hearth-I, i.e. entryhearth (110), Hearth-II (120), Hearth-III (130), Hearth IV (140), andHearth-V (150). Carbonaceous material feed (101) is introduced in thegasification zone in Hearth-I. Inside the gasification zone, solid fromHearth-I, i.e. entry hearth, is transferred to Hearth-II; solid fromHearth-II is transferred to Hearth-III; solid from Hearth-III istransferred to Hearth-IV, and solid from Hearth-IV is transferred toHearth-V. Solid comprising unconverted portion of carbonaceous materialis transferred from Hearth-V of gasification zone into the burn-up zone(500). A first molecular oxygen containing gas is supplied to differentgasification hearths though gas inlets 611, 621, 631, 641, and 651 thatare attached to Hearth-I, Hearth-II, Hearth-III, Hearth-IV, and Hearth-Vrespectively. In one aspect, no molecular oxygen containing gas isintroduced into Hearth-I. A second molecular oxygen containing gas issupplied to the burn-up zone through gas inlet 202.

Gaseous product from burn-up zone is transferred to gasification zoneand combined with gaseous product from gasification zone to produce araw syngas stream (not shown on diagram) that is passed through aconnecting zone or throat (300) into the tar reduction zone (400). Athird molecular oxygen containing gas is introduced into the throatthough gas inlet 301 wherein the raw syngas stream and third oxygencontaining gas are mixed. In one aspect, the third molecular oxygencontaining gas is introduced directly into the tar reduction zone (notshown on diagram). In one aspect, the third molecular oxygen containinggas is introduced into the throat as well as into the tar reduction zone(not shown on diagram). The mixture of raw syngas and oxygen containinggas is subjected to treatment with heat in the tar reduction zone. A hotsyngas is thus produced and a stream of hot syngas (405) is removed fromthe tar reduction zone.

EXAMPLES Example I

A gasification apparatus comprising a gasification zone, a burn-up zoneand tar destruction zone was used in this example. Carbonaceous materialfeed was introduced into the gasification zone. A first molecular oxygencontaining gas was supplied to the gasification zone at the rate ofabout 10 to about 15 lb-moles per ton of water-free carbonaceousmaterial to gasify a portion of the carbonaceous material and produce afirst gaseous product.

Remaining carbonaceous material from the gasification zone was forwardedto the burn-up zone wherein a second molecular oxygen containing gas wassupplied at the rate of about 10 to about 15 lb-moles per ton ofwater-free carbonaceous material to gasify additional portion ofcarbonaceous material and produce a second gaseous product.

The first and second gaseous products were combined to produce a rawsyngas that was allowed to enter a tar destruction zone. A thirdmolecular oxygen containing gas was supplied to the tar destruction zoneat the rate of about 20 to about 30 lb-moles per ton of water-freecarbonaceous material. A hot syngas was produced and removed from thetar destruction zone.

The gasification zone was also fed a stream of carbon dioxide at therate of about 10 to about 15 lb-moles per ton of water-free carbonaceousmaterial. The burn-up zone was fed a stream of carbon dioxide at therate of about 2 to about 5 lb-moles per ton of water-free carbonaceousmaterial.

Additionally, about 20 to about 30 lb-moles of air per ton of water-freecarbonaceous material entered the gasification process due to leakage.

For a ratio of oxygen input to burn-up zone to total oxygen input ingasification and burn-up zone in the range of about 0.4 to about 0.6,conversion of organic or gasifiable or volatile material content ofcarbonaceous material was above 90% and generally in the range of about95 to about 98%. Ratio of the carbon content of residual ash produced tothe carbon content of carbonaceous material feed was less than about 0.1and generally in the range of about 0.04 to about 0.10. The ratio ofCO/CO₂ in the hot syngas produced was greater than about 0.75; the ratioof CO/H₂ in the hot syngas produced was greater than 1.5; the ratio ofCO/(CO+CO₂) was greater than about 0.4.

For a ratio of oxygen input to burn-up zone to total oxygen input ingasification and burn-up zone less than about 0.4, conversion of organicor gasifiable or volatile material content of carbonaceous material wasabout 82%. Ratio of the carbon content of residual ash produced to thecarbon content of carbonaceous material feed was about 0.3.

While the invention herein disclosed has been described by means ofspecific embodiments, examples and applications thereof, numerousmodifications and variations could be made thereto by those skilled inthe art without departing from the scope of the invention set forth inthe claims.

1-32. (canceled)
 33. A gasification apparatus comprising: a gasificationzone that includes one or more hearths; a burn-up zone continuous withthe gasification zone, the burn-up zone including one or more hearths,wherein the gasification and burn-up zones are effective for providing araw syngas having a CO/CO₂ molar ratio greater than about 0.75 and ratioof carbon content of solid ash to carbon content of carbonaceousmaterial feed is less than about 0.1; and a tar destruction zoneeffective for receiving the raw syngas from the gasification and burn-upzones through a connecting zone, wherein the connecting zone includes atleast one gas inlet.
 34. The gasification apparatus of claim 33 whereinthe gasification zone includes up to 10 hearths.
 35. The gasificationapparatus of claim 33 wherein the burn-up zone includes up to 5 hearths.36. The gasification apparatus of claim 33 further comprising at leastone solids transfer device effective for moving carbonaceous materialfrom the gasification zone to the burn-up zone.
 37. The gasificationapparatus of claim 33 further comprising at least one gas inlet in thegasification zone, burn-up zone and tar destruction zone.